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971.
Zang Q Keire DA Wood RD Buhse LF Moore CM Nasr M Al-Hakim A Trehy ML Welsh WJ 《Analytical and bioanalytical chemistry》2011,399(2):635-649
Heparin, a widely used anticoagulant primarily extracted from animal sources, contains varying amounts of galactosamine impurities.
Currently, the United States Pharmacopeia (USP) monograph for heparin purity specifies that the weight percent of galactosamine
(%Gal) may not exceed 1%. In the present study, multivariate regression (MVR) analysis of 1H NMR spectral data obtained from heparin samples was employed to build quantitative models for the prediction of %Gal. MVR
analysis was conducted using four separate methods: multiple linear regression, ridge regression, partial least squares regression,
and support vector regression (SVR). Genetic algorithms and stepwise selection methods were applied for variable selection.
In each case, two separate prediction models were constructed: a global model based on dataset A which contained the full range (0–10%) of galactosamine in the samples and a local model based on the subset dataset B for which the galactosamine level (0–2%) spanned the 1% USP limit. All four regression
methods performed equally well for dataset A with low prediction errors under optimal conditions, whereas SVR was clearly
superior among the four methods for dataset B. The results from this study show that 1H NMR spectroscopy, already a USP requirement for the screening of contaminants in heparin, may offer utility as a rapid method
for quantitative determination of %Gal in heparin samples when used in conjunction with MVR approaches. 相似文献
972.
Li B Zang SQ Ji C Liang R Hou HW Wu YJ Mak TC 《Dalton transactions (Cambridge, England : 2003)》2011,40(39):10071-10081
The reactions of 1,2,3,4-benzenetetracarboxylic acid (H(4)mpda) and different silver(I) salts under hydrothermal or solvent evaporation conditions yielded four unusual coordination complexes with interesting frameworks: [Ag(4)(mpda)](n) (1), {[Ag(2.5)(mpda)(bpy)(2)]·[Ag(bpy)]·[Ag(bpy)(H(2)O)]·(NO(3))(0.5)·(H(2)O)(9)}(n) (2), {[Ag(5)(mpda)(2)(bpy)(4)]·[Ag(bpy)]·[Ag(bpy)(H(2)O)]·[Ag(bpy)(H(2)O)]·(H(2)O)(16)}(n) (3), {[Ag(2)(mpda)(H(2)O)]·[Ag(bpy)]·[Ag(bpy)]}(n) (4) (bpy = 4,4'-bipyridine). Complex 1 displays a novel (3,4,7)-connected {4.6(2)}{4.6(5)}{4(2).6(13).8(5).10} topology, in which the carboxylic groups of the mpda(4-) ligand adopt variable coordination modes. In 1, besides Ag-O coordination bonding, AgAg and Agaromatic intermolecular interactions also make their appearance. In complexes 2-4, rare architectures comprising three or four isolated coordination polymers within the same crystalline structure have been obtained, respectively. In 2 and 3, neighboring layers are linked together through water tapes into a three-dimensional supramolecular architecture, which is also consolidated by π···π stacking, while independent infinite rod-like polymer chains fill the void space between layers. Interestingly, an anionic (H(2)O-NO(3)(-))(n) layer, built from water tapes and nitrate anions as well as consolidated by the mpda(4-) ligands, has been structurally identified in compound 2. A new water tape constructed from alternating tetramers and decamers has been obtained in compound 3. In compound 4, a right-handed helical chain and two rod-like polymeric chains are interconnected through host-guest molecular recognition to generate a three-dimensional chiral supramolecular architecture. Bulk materials for 1 and 4 have second-harmonic generation activity, being approximately 0.6 and 0.4 times that of urea. The IR spectra, thermogravimetric analysis and luminescent properties of all compounds were also investigated. 相似文献
973.
He JianJun Hu Jun Xu ShiWei Chen ZhiQiang Zhang XueYing Wang JianSong Yu XiangQing Zhang LiYong Li Long Yang YanYun Ma Peng Zhang XueHeng Hu ZhengGuo Guo ZhongYan Xu Xing Yuan XiaoHua Lu Wan Yu YuHong Zang YongDong Tang ShuWen Ye RuiPing Chen JinDa Jin ShiLun Du ChengMing Wang ShiTao Ma JunBing Liu LongXiang Bai Zhen Lei XiangGuo Sun ZhiYu Zhang YuHu Zhou XiaoHong Xu HuShan Su Jun Li ErTao Wang HongWei Tian WenDong Li XiangQing 《中国科学:物理学 力学 天文学(英文版)》2011,54(1):32-36
The proton resonant properties in 18Ne, which determine the reaction rate of the key stellar 14O(α,p)17F reaction, have been studied by using a technique of proton resonant elastic scattering of 17F+p. A 4.22 MeV/nucleon 17F radioactive ion (RI) beam was produced via a projectile-fragmentation reaction, and separated by a Radioactive Ion Beam Line in Lanzhou (RIBLL). By bombarding a thick (CH2) n target, the energy spectra of the recoiled protons were measured by two ΔE-E silicon telescopes at the center-of-mass scattering angles of θ c.m.≈175°±5°, θ c.m.≈152°±8°, respectively. Several proton resonances in 18Ne were observed clearly. A further R-matrix analysis of the experimental data is under way to determine the resonant parameters. The present work reports the preliminary results briefly. 相似文献
974.
Bo Li Shuang-Quan Zang Can Ji Thomas C.W. Mak 《Journal of organometallic chemistry》2011,696(15-16):2820-2828
A series of five silver coordination polymers [(AgL1)·(AgCF3COO)5·(H2O)3] (1), [(AgL1)2·(AgCF3COO)11·(H2O)6] (2), [(AgL2)·(AgCF3COO)3·(H2O)] (3), [(AgL3)·(AgCF3COO)4·(CH3CN)2] (4), and [(AgL3)·(AgCF3COO)7·(CH3CN)2·(H2O)2] (5) have been constructed from three flexible anionic ligands HL1, HL2, and HL3 (HL1 = 1-chloro-2-(prop-2-ynyloxy)benzene, HL2 = 1-chloro-3-(prop-2-ynyloxy)benzene, HL3 = 1-chloro-4-(prop-2-ynyloxy)benzene). In these compounds, the invariable appearance of the μ4- and μ5-ligation modes of the ethynide moiety affirms the general utility of the flexible silver-ethynide supramolecular synthon o-, m-, p-Cl?C6H5OCH2CC?Agn (n = 4, 5) in coordination network assembly. Among them, Ag?Cl interaction plays a vital role in assembling the supramolecular structures in complexes 1?3. 相似文献
975.
With BIMB ligand, we have successfully obtained and characterized three novel entangled inorganic-organic hybrid compounds by choosing different metal ions, that is, [Ni(BIMB)2(γ-Mo8O26)0.5]·3H2O (1), [Zn(BIMB)2(γ-Mo8O26)0.5] (2), and [Cu3(BIMB)4(H2O)(δ-Mo8O26)Cl2]·3H2O (3) (where BIMB=1,4-bis(1-imidazolyl)benzene). Compound 1 is a 2-fold interpenetration 4-connected 3D framework with the short Schläfli symbol of (4×64×8)2(42×62×82), in which octamolybdate anion shows γ-isomer; 2 exhibits a (5,6)-connected 3D self-penetrating topological motif with the short Schläfli symbol of (4×57×62)2(42×511×72), and 3 shows a (4,6)-connected self-penetrating 3D framework with the short Schläfli symbol of (42·52·6·7) (44·5·69·8) (54·62) whose octamolybdate has δ-isomer. In addition, the optical band gaps of these three compounds have been measured, which are 2.98 eV for 1, 3.42 eV for 2, and 2.88 eV for 3. Moreover, 2 has photoluminescent property, which can be attributed to ligand-to-metal charge-transfer (LMCT) band. 相似文献
976.
Kong W Wang J Xing X Xiao X Zhao Y Zang Q Zhang P Jin C Li Z Liu W 《Analytica chimica acta》2011,(2):250-256
Multi-hydroxyl amines including tris(hydroxymethyl)aminomethane (Tris), serinol and ethanolamine were selected as weak affinity ligands using a rapid screening by quartz crystal microbalance (QCM) biosensor. Based on the specific recognition between the ligands and two proteins, lysozyme (LZM) and cytochrome c (Cyt c), a weak affinity chromatography method was developed for specific separation of the two proteins. The frontal analysis results showed that the apparent dissociation constants (KD) of ligand–protein complexes were all in the order of weak affinity (10−4 M). By weak affinity columns modified with the three multi-hydroxyl amines individually, LZM and Cyt c were baseline separated as retarded peaks from non-specific protein and each other in a single cycle of loading and eluting. Moreover, the Tris-modified column typically showed the satisfactory repeatability and stability as a new type of weak affinity columns. The present strategy composed of QCM selecting and affinity chromatography separating was promising to extend the variety of weak affinity ligands and develop inexpensive specific affinity methods for separation and purification of multiple proteins on one single column. 相似文献
977.
D.?Y.?Zang H.?P.?Wang F.?P.?Dai D.?Langevin B.?WeiEmail author 《Applied Physics A: Materials Science & Processing》2011,102(1):141-145
We report a solidification mechanism transition of liquid ternary Co45Cu45Ni10 alloy when it solidifies at a critical undercooling of about 344 K. When undercooling at ΔT<344 K, the solidification process is characterized by primary S (Co) dendritic growth and a subsequent peritectic transition.
The dendritic growth velocity of S (Co) dendrite increases with the rise of undercooling. However, once ΔT>344 K, the solidification velocity decreases with the increase of undercooling. In this case, liquid/liquid phase separation
takes place prior to solidification. The minor L2 (Cu) droplets hinder the motion of the solidification front, and a monotectic transition may occur in the major L1 phase. These facts caused by metastable phase separation are responsible for the slow growth at high undercoolings. 相似文献
978.
979.
Jian‐mei Li Rong‐rong Zang Min Li Dong Kou Juan Du 《Journal of Dispersion Science and Technology》2013,34(5):681-687
The kinetics of hydrolysis of p‐nitrophenyl picolinate(PNPP) catalyzed by metallomicelles formed from Cu (II), Ni (II) Schiff base complexes (CuL, NiL) and CTAB micelle were investigated in the pH range of 6.0–9.0 at 30°C. For the Cu (II) Schiff base complex CuL, the apparent rate constants (k obsd) of PNPP hydrolysis initially increased with the increasing pH of reaction media, then fell off. For the Ni (II) Schiff base complex NiL, the k obsd always increased with the increasing pH. The kinetic and thermodynamic parameters were calculated. The hydrolysis rate of PNPP catalyzed by Cu (II) complex was much larger than that by Ni (II) complex in CTAB micellar solution. The catalytic mechanism of the PNPP hydrolysis was discussed in detail, and the possibly active specie for the catalytic hydrolysis of PNPP was the monohydroxo metal complex. 相似文献
980.
Qiu Hua Wu Shuai Hua Zhang Chun Wang Xiao Huan Zang 《International journal of environmental analytical chemistry》2013,93(8):884-893
A simple, rapid, efficient, and environmentally friendly method for the determination of some triazine herbicides (simazine, atrazine, prometone, ametryn and prometryne) in water samples was developed by ultrasound-assisted emulsification microextraction (USAEME) coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD). The main parameters that affect the extraction efficiencies, such as the kind and volume of the extraction solvent, ultrasound emulsification time and salt addition, were investigated and optimized. Under the optimum conditions, the method was sensitive and showed a good linearity within a range of 0.5 to 200?ngm?L?1 for simazine, atrazine, prometone, ametryn and prometryne, with the correlation coefficients (r) varying from 0.9993 to 0.9998. High enrichment factors were obtained ranging from 148 to 225. The limits of detection (LODs) were in the range between 0.06 and 0.1?ngm?L?1 and the limits of quantification (LOQs) were in the range between 0.2 and 0.3?ngm?L?1. The recoveries of the analytes from water samples at spiking levels of 5.0 and 50.0?ngm?L?1 were ranged from 82.4% to 107.0%. The relative standard deviations (RSDs) varied from 3.0% to 4.6%. The results demonstrated that the USAEME-HPLC-DAD method was an ef?cient pretreatment and enrichment procedure for the determination of triazine pesticides in real water samples. 相似文献